Chloroprene rubbers, which are superior in mechanical properties, weather resistance, flame resistance, and others, have been used widely as materials for industrial rubber products. Under increasingly severe demand in performance to these industrial rubber products, there exists a need for a chloroprene rubber that is improved in abrasion resistance and ozone resistance yet retaining these properties.
Known as the means of improving the abrasion resistance of chloroprene rubbers are a means of polymerizing chloroprene monomers using an alkylxanthogen sulfide as chain-transfer agent (see Patent Document 1) and a means of forming a chloroprene rubber by polymerization and plasticizing the rubber in the presence of a tetraalkylthiuram disulfide having 3 to 7 carbon atoms during plasticization (see Patent Document 2).
Also known as the technology for improving the ozone resistance of chloroprene rubbers is a means of adding a thiazole compound, thiuram compound, or thiourea compound to a rubber composition containing a chloroprene rubber and an ethylene-propylene-diene copolymer rubber (see Patent Document 3).